Sandfish and medium conditions

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Sandfish and medium conditions

Sarah Steinmetz is an IGERT trainee pursuing a PhD in Bioengineering. She works in the laboratory of physicist Dan Goldman. Organisms like the desert sandfish lizard must locomote on and within a complex granular medium. Sarah investigates how the sandfish accommodates to different medium conditions. She used synchronized x-ray and visible light imaging with electrically-recorded muscle activity during above-surface and subsurface movement. While moving on the surface, the sandfish does not exhibit lateral bending and does not activate its back muscles. During subsurface sand-swimming, the sandfish uses a single-period traveling wave of body undulations. Muscle activation intensity only changes slightly between a closely and loosely packed medium. Overall, the difference in the EMG pattern can be attributed to the unique physics of the granular media in which the sandfish interacts. This was the first study of its kind to investigate muscle activation in a desert sand-swimmer.